FR2539940A3 - ELECTRIC HEATING ELEMENT, PARTICULARLY FOR SMOOTH COOKING SURFACES - Google Patents

Abstract

ELECTRIC HEATING ELEMENT, IN PARTICULAR FOR SMOOTH COOKING SURFACES, INCLUDING AN INSULATING ELEMENT 2 WHICH DEFINES A HEATING SURFACE 3 TO WHICH IS ASSOCIATED A PLURALITY OF INDEPENDENT RESISTANCE ELEMENTS 4. THESE ESSENTIAL RESISTANCE ELEMENTS 4 ARE INDEPENDENT SHAPED OF CONCENTRIC ALTERNATE SPIRALS TO ACT GLOBALLY ON THE HEATING SURFACE 3, AND THEY CAN BE SUPPLIED WITH ELECTRIC CURRENT SELECTIVELY, INDIVIDUALLY OR IN COMBINATION WITH THEM. IN ADDITION, A TEMPERATURE LIMITER 10 IS PROVIDED. THE ELECTRIC HEATING ELEMENT ALLOWS A DIFFERENTIATION OF TEMPERATURES ON THE COOKING SURFACE DEPENDING ON THE TYPE OF COOKING DESIRED. THE TEMPERATURE LIMITER ALLOWS THE ELECTRICAL SUPPLY TO BE INTERRUPTED TO PREVENT HAZARDOUS OVERHEATING OF THE COOKING SURFACE.

Description

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  The subject of the invention is a heating element

  particularly applicable to smooth cooking surfaces

glass ceramic.

  We know that the heating elements for over-

  smooth faces are generally constituted by a metal shell containing an insulating layer preferably of the microporous type based on silica airgel containing a fiber

  reinforcement and / or an opacifier.

  On the insulating layer mentioned, there is a resistance spiral usually consisting of a bare wire of a suitable material wound in a spiral and fixed to the

  insulating layer by hooks or adhesive.

  Alternatively, one can interpose between the insulating layer described above and the resistance spiral a

  profiled ceramic fiber cup that defines a location

  appropriate cement for the spiral mentioned above.

  There are also heating elements provided with several resistance elements; in this case between a

  resistance element and the autreton has an insulating layer

  able to physically divide the two heating zones.

  Heating elements of this type are inserted

  res below a surface constituted for example by a vitreous ceramic material which transmits the heat received from

  radiant or convective heating elements

  kitchen utensils placed on said surface.

  In practice - heating elements of the type

  known generally have thermoregulatory capacities-

  which are not proportionate to the actual needs of the user who must be able to vary the amount of heat transmitted to the cooking surface in a way

  gradual and within wide limits.

  Reaction times of heating elements

  of the known type are moreover inadequate for supplying

  different temperature variations of the cooking surface; in addition, if each heating element is provided with several resistance elements, the layer, isolaote between

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  each element of resistance produces inequalities of

heating the cooking surface.

  In light of these problems, the main purpose

  pal of the invention is that of eliminating the drawbacks indicated above by providing an electric heating element in particular for smooth cooking surfaces, capable of providing considerable temperature differentiation on said surface, for any type of cooking-. Another object of the invention is to provide an electric heating element capable of being inserted with the cooking surface in cookers or spaces arranged to be equipped with tables of

  baking of the baking pan type allowing the use

  control switches normally used for

said plates.

  Another object of the invention is that of

  read a heating element of great reliability and adaptability. These and other objects are achieved by an electric heating element, in particular for smooth cooking surfaces, comprising an insulating element which defines a heating surface with which a plurality of independent resistance elements is associated, characterized in that said resistance elements are arranged essentially in alternating concentric spirals in order to act globally on said heating surface and in that they can be supplied with electric current selectively individually and / or in combination

between them.

  Other characteristics and advantages

  get better from the detailed description of an element of

  electric heating according to the invention illustrated by way of example in the anneoé drawing in which: Fig l shows a top view of this heating element according to the invention;

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  Fig 2 shows a section along line A-A of Figure 1 of the same element;

  Fig 3 illustrates a detail B of the delivery area

  between the cup and one of the resistance elements.

  Referring to the figures indicated, the electric heating element according to the invention is

  indicated as a whole by the reference numeral 1.

  It essentially consists of an insulating element 2 which defines a heating surface 3 at which

  is associated a plurality of elements of inde

  pendant 4 In particular, the heating element 1 may consist of a metal shell 5 carrying a microporous insulating layer 6, for example in airgel

  silica containing a reinforcing fiber and / or an opaci-

  trusting, and on which a cup 7 can be placed,

  made for example of fiber-ceramic.

  According to the invention resistance elements

  are arranged essentially in the form of concentrated spirals

  triques and alternates; this, unlike the elements of

  known heating, and also thanks to the elimination of the

  insulating che which physically divides the heating zones,

  allows a clear qualitative improvement in the distribution

  heat from the cooking surface.

  Preferably elements of resistance

  have different electrical resistance characteristics

  between them so as to further increase the

  possibilities to regulate the heat produced; in order to facilitate-

  ter the electrical connection of the heating element to

  supply network, the ends 8 of said re-

  sistance can be connected to connections 9 of known type preferably placed at the periphery of the insulating element.

  In addition, provision is made for the application of a limit

  temperature sensor capable of preventing the surface of

  glass ceramic firing exceeds a certain temperature

re critical.

  The limiter in a preferred embodiment has a bar 11 sensitive to heat, placed essentially in diametric extension relative to the heating element, and supported for example by notches made in the cup. Said bar it is connected to a body of

  command indicated schematically by 13, which, once reached

  te a certain temperature of the glass ceramic surface, interrupts the electrical supply of one or

  several of said resistance elements.

  To selectively supply said elements

  resistance of electric current which can

  be connected to a switch 14 whose number of positions

  switching states will be equal to the number of possible supply combinations of the resistance elements plus a position to interrupt the current supply to the heating element; in practice, this allows the resistance elements to be supplied individually or in groups according to the possible combinations, so as to increase

  considerably the possibilities of regulating the trans-

put on the cooking surface.

  The resistance elements are fixed to the cup 7 or more generally to the insulating element 2 is preferably carried out by an adhesive 15 as illustrated in FIG. 3, or by hooks not shown as

than of known type.

  In addition, the cup 7 can advantageously be replaced by a single microporous insulating layer, preferably in silica airgel with ceramic fiber, with the optional addition of an opacifier and / or reinforced with binders and / or subjected to a heat treatment. In

  in this case, the resistance elements 4 will be fixed directly-

  similarly to the single insulating layer.

  Preferably, the insulating element or the cup present in the heating surface carrying the resistance elements of the housings 16 defining the zone of location of each resistance element so as to

  give greater stability to it.

  The operation of the heating element

  form of the invention appears obvious on the basis of what has been described and illustrated; in particular the energy

  power is supplied to one or more terminals of

  through the switch connected to one or more

  of them according to a classic scheme.

  By selecting one of the various positions of

  switching, it is thus possible to supply one or more

  resistance elements in different combinations

  annuities, obtaining a temperature differentiation on the glass ceramic surface depending on the type of

cooking we want to% achieve.

  The temperature monitor, also connected

  according to a classic scheme, allows to interrupt the feeding

  tion by running to one or more of the resistance elements

  this, in order to avoid dangerous overheating of the glass ceramic surface, keeping at the same time

  surface temperature at an optimal level.

  Thanks also to their compact structure, the

  heating elements thus produced can be inserted in stoves or spaces fitted out to be fitted on hobs of the cast iron plate type, possibly using the switching controls

for these plates.

  Obviously the materials used as well as the dimensions and the shapes can be any

  according to requirements and state of the art.

Claims (5)

  1 Electric heating element, in particular   binder for smooth cooking surfaces, comprising an insulating element (2) which defines a heating surface (3), to which is associated a plurality of independent resistance elements (4), characterized in that said 'resistance elements (4) are arranged essentially in the form of alternating concentric spirals in order to act globally on said heating surface (3) and in this   that they can be selectively supplied with electrical energy   stick, individually and / or in combination with each other.   2 heating element according to claim 1, characterized in that said resistance elements (4) have characteristics of electrical resistance   equal to each other or different.   3 heating element according to claim 1 or 2, characterized in that it comprises a temperature limiter (10) connected to one or more of said elements resistance (4).   4 Heating element according to any one   of the preceding claims, characterized in that said   resistance elements (4) are connected to a switch (14) having a number of switching positions allowing different power supply combinations to said elements   resistance elements (4) plus a position for inter-   breaking the electrical supply to said heating element.   5.Heating element according to any one   of the preceding claims, characterized in that it   comprises a metal shell (5) supporting a microporous insulating material (6), with which is possibly associated a cup (7), preferably made of preformed fibroceramic, said resistance elements (4) being associated with the   upper surface of said insulating element (6) or possibly- ment of said cup (7).